Last updated: 12-12-01

Stage:Guider TV Focus
ID #: KDTV-001A
Engineer: D. Cowley (T. Freeman)

Mechanical Description of Stage:

Electronic Description of Stage:

The TV Focus stage uses Controller #1, amplifier 1A and is connected to the B axis.

Standard constrained rotary stage. Movement is constrained to the motion of the focus mechanism. The stage uses an EL-1236 Stage Interconnect Box, SPDTprimary limits, DPDT secondary limits, and an optical fiducial. The first limit the stage encounters is the software limit. Just beyond the software limit is the primary hardware limit. If the stage makes it past these limits, the secondary limit will break the connection to the motor itself. The software will inform the user that the secondary limit has been encountered. If this happens, the only way to back out of these limits is to manually move the motor shaft. The optical fiducial is used to define the home point. Note that the optical interrupter is only enabled when the stage is moving. This means that the IR emmitter is turned offwhen the focus stage is not moving, e.g., during exposures.

Required setting accuracy :

Performance requirements and design goals
Component Requirements 1
Motors: Galil #50-1000  
Limits 2: Microswitch BZ-2RW822-A2 "primary limit" and DT-2RV22-A7"secondary limit"  
Fiducials: TRW #OPB-970-T55 (Optical)  
Encoders: BEI #MX213-25-1000 (4000 quadrature counts/rev)  
Air Cylinders:-  
Air Solenoids:-  
  1. Speed, temperature, accuracies, electrical power, pressurized air,lubricant, coolant, N2 purge, ...
  2. Primary (inner) and secondary (outer) limits. These can be magnetic,optical, or physical contact

Manufacturer's specifications and limitations
Component Maximum Operating Condition  Safe Ops Condition  Requirements 
Motors: Galil #50-1000
3750 RPM, 205 oz-in peak Torque

Final Mechanical Assembly and Testing Results

Tests performed by: K. Dietsch 6-28-00, C. Harper 12-12-01

Motor tuning parameters under different spacialorientations and environment
Parameter    Set To:
PID Filter: KD:
Acceleration (pulses/sec^2):  
Deceleration (pulses/sec^2):  
Speed (pulses/sec):  
Set the following parameters:   CN 1,-1       CB 2    
  1. Uphill defined as motor (or driven end of shaft) in lowest position

Rotary Stage (constrained)
Distance from "home"  Position Motor Counts  Time to Reach
Software Limits:  Forward
13 Seconds limit to limit 
13 Seconds limit to limit 
Primary (inner) Limits:  Forward
Secondary (outer) Limits:  Forward
           *Focus is set at +960 (12-11-01)
** reverse limit switches kick back after being enabled

Resolution of Stage
Encoder Counts per single rotation of focus wheel: Counts / arcsecond focus blur
On Motor


*Linear motion "stage" is actually internal to Cannon lens.  But itappears to be a rotory stage.

Mechanical Drawing(s) # D8140, #D0920

Electronic Drawing(s) # EL-3051

Sign conventions are such that a positive motion of the motor turns the motor in a CW direction as viewed from the drive shaft looking back into the motor, and will drive the stage towards the forward limit.